Celldex Study Finds Most Patients Symptom-Free From Angioedema After One Year; Retail Bulls Stay Guarded

Retail investor chatter around Celldex Therapeutics spiked on Sunday following new Phase 2 data showing barzolvolimab provided “profound long-term” relief from angioedema in patients with chronic spontaneous urticaria (CSU).

Celldex shares closed 4.5% higher at $21.26 on Friday.

The company presented updated 52-week results at the European Academy of Allergy and Clinical Immunology (EAACI) 2025 Congress in Glasgow, showing that 77% of patients on barzolvolimab were angioedema-free at Week 52. 

The antibody therapy also showed up to 87% of patients reported “clinically meaningful” improvements in angioedema activity scores (AAS7).

Barzolvolimab targets KIT, a receptor tyrosine kinase involved in mast cell regulation. 

In CSU, mast cells drive persistent inflammation and swelling even after standard antihistamine therapy fails.

Patients with severe CSU and angioedema frequently endure disfigurement and debilitating pain, said Diane C. Young, MD, Chief Medical Officer at Celldex. 

Additional data showed an 86% mean reduction in angioedema activity in the 150 mg group and 82% in the 300 mg every-8-weeks group. 

Patients remained angioedema-free for 72% of the year-long treatment period.

Retail sentiment on platforms such as Stocktwits and Reddit turned sharply bullish over the weekend, with several users highlighting the durability of symptom control and potential differentiation from existing CSU treatments like Novartis’ Xolair.

The 208-patient Phase 2 trial had previously met all primary and secondary endpoints at 12 weeks. 

A global Phase 3 program is underway, targeting antihistamine-refractory CSU patients, including those previously treated with biologics.

On Stocktwits, retail sentiment was ‘bearish’ amid ‘extremely high’ message volume.

Celldex stock has declined 17.6% so far in 2025.

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